There are commonly unsolved difficult problems in the ground tests and laboratory hardware-in-the-loop tests of the inertial and integrated Guidance, Navigation, and Control (GNC) system on-board a military missile or a vehicle such as aircraft, spacecraft, ship, and car.
In the ground test, since the vehicle is stationary, the IMU in the GNC system can not produce dynamic electronic signals for it is a self-contained device. In other words, it is unable to test the accuracy and errors of the GNC system installed on-board vehicle while it is stationary. If the IMU and the GNC system are installed on-board a ground vehicle such as a car or a combat tank, the tester can still process a motion test for the IMU by actually driving the ground vehicle in relatively low cost. However, if the vehicle to be test is an aircraft or even a spacecraft, the cost and labors for actual-fly test are ultimately expensive.
In order to verify the correctness and/or evaluate the performance of an integrated GPS/INS system on the ground, before a real flight test or in the laboratory, the GPS/INS system must be excited by its dynamic sensor signals, as if the GPS/INS system were under an actual dynamic flight condition. Motion table approaches can put the GPS/INS system into actual motion and provide dynamic excitation to the system. But these approaches are usually costly, inconvenient, and even inaccurate.
A straightforward method for dynamic ground testing is the application of the flight motion tables that provide the motion of the vehicle during emulated flight in an installed system environment. With this method, the GPS receiver receives actual satellite RF signals and the IMU produces dynamic inertial measurement signals itself, for the integrated system is actually in motion. But this test method is not a viable solution. It needs a large set of testing equipment, its operational cost is high, its dynamic motion is limited, and its data acquisition during the emulation is not convenient. In fact, the motion table method is very much limited in the dynamic trajectory emulation. The rate table can only produce angular motion in one axis and it can not produce transnational motion. The centrifuge can only produce one or two direction acceleration and one angular rate and the motion of the IMU system is limited to a small space.